Detailed Description

In addition, it may contain indexes to improve the performance in the retrieval of the table's data and keys, and to define semantic rules for the table.

Note: All properties and columns of a table could by modified before it is appended to a database. In that case, the service is in fact a descriptor. On existing tables, a user might alter columns, add or delete columns, indexes, and keys depending on the capabilities of the database and on the user's privileges.